232 results about "Antifouling coating" patented technology

The invention discloses cerium oxide / piezoelectric material composite nano-enzyme for an antifouling coating as well as a preparation method and application of the cerium oxide / piezoelectric material composite nano-enzyme, and belongs to the technical field of material chemistry and marine protection. The preparation method of the composite nano-enzyme comprises the following steps: dispersing a metal cerium source and a piezoelectric material source in a solvent according to a mass ratio of 1: (1-5), carrying out phase formation and composite treatment, and collecting a solid product after treatment, thereby obtaining the composite nano-enzyme. The composite nano-enzyme can be used for marine antifouling paint to form a functional material system capable of realizing self-driven antifouling by directly utilizing mechanical energy such as ocean waves, vibration and the like. According to the system, mechanical energy is converted into electrochemical energy to drive in-situ generation of H2O2, and Ce < 3 + > / Ce < 4 + > redox cycle is utilized to efficiently convert H2O2 into ROS, so that sustainable antibacterial and anti-biological adhesion effects are achieved, toxic substances are not released, and the system belongs to an environment-friendly protection technology.

An antifouling coating composition comprising: (A) a binder comprising a (meth) acrylic copolymer (i) comprising a silyl ester group; (B) from 2.0 to 30% solids volume, such as from 5.0 to 20% solids volume, of cuprous oxide; and (C) 2.0 to 65% solids volume, such as 10 to 55 solids volume% of hollow spheres.

The present application relates to the technical field of marine antifouling coating, in particular to an organic-inorganic composite antifouling coating, a preparation method and application thereof.The raw materials of the antifouling coating include A component and B component in a weight ratio of (7-9):1, wherein the A component includes the following raw materials in parts by weight: 50-75 parts of hydroxyl silicone resin, and 5-20 parts of antifouling agent; the B component includes the following raw materials in parts by weight: 10-30 parts of modified silicone resin, 20-80 parts of silica gel, and 1-10 parts of auxiliary agent; the hydroxyl silicone resin is a two-end hydroxyl silicone oil, and the hydroxyl content in the hydroxyl silicone resin is 0.025-3 wt%.The present application provides a low surface energy antifouling coating applied to marine vessels, and the coating has a uniform and staggered low surface energy surface and a hydrogel surface.The low surface energy antifouling coating has good film elasticity, low surface tension, good impact resistance, high scratch resistance, and a long effective service life of more than seven years.

The application discloses an intrinsic antifouling coating composition based on furan dioxime antibacterial cross-linking agent and application. The intrinsic antifouling coating composition comprises an A component and a B component, the A component comprises a zwitterionic modified hydroxyl silicone oil, and the B component comprises a furan dioxime antibacterial cross-linking agent. After forming a coating, the organic silicon segment, the zwitterionic segment and the furan dioxime segment in the intrinsic antifouling coating composition can respectively endow the coating with dynamic antifouling performance, static antifouling performance and sterilization performance, meanwhile, the coating composition realizes intrinsic triple antifouling without any antifouling agent and related fillers, and is suitable for efficient antifouling of the surface of marine equipment.

Provided is an antifouling coating composition that can exhibit excellent properties even when an antifouling coating film has been repeatedly applied, without a deterioration in the dissolution stability of the coating film and without the occurrence of coating film abnormalities such as peeling and cracking.　The present invention provides a copolymer for antifouling coating compositions wherein the copolymer A for antifouling coating compositions is obtained by the copolymerization of a monomer mixture comprising a monomer (a), a monomer (b), and a monomer (c); the monomer (a) is given by general formula (1); the monomer (b) is given by general formula (2); the monomer (c) is a monomer other than the monomer (a) and monomer (b), that is copolymerizable with the monomer (a) and monomer (b); the proportion of the monomer (a) in the monomer mixture is 25-60 mass%; the copolymer has a molecular weight distribution (Mw / Mn) of at least 5.0; and the copolymer does not contain the sulfur atom.

The utility model relates to turf base cloth processing technical field, concretely relates to turf base cloth nanometer antifouling coating spraying device, including machine body, the left -hand side fixed connection of machine body has the support, the inside rotation of support is connected with unwinding roller, the right -hand side rotation of machine body is connected with the winding roller, the top of machine body inside rotation is connected with the cloth guide roller, the inside symmetry fixed connection of machine body has fixed frame, the top of fixed frame is connected with the sliding rod of sliding, the top fixed connection of sliding rod has the ball of impact, the first spring of outside of sliding rod and located fixed frame inside top end cover, the outside fixed connection of machine body has storage box, the outside fixed connection of storage box has water pump, compare with existing turf base cloth nanometer antifouling coating spraying device, the utility model through the design of extruding block and ball of impact, can complete the base cloth impact fast, spread its inside gap, the antifouling coating penetration is convenient, has improved the overall practicability greatly.

The invention discloses a preparation method and application of a super-hydrophobic antifouling coating with a self-repairing function, and belongs to the technical field of modification of self-repairing super-hydrophobic coatings of textiles. The method comprises the following steps: mixing boric acid, ethanol and n-octadecyltriethoxysilane, heating and stirring to completely dissolve the boric acid to obtain a mixed solution; and dropwise adding water into the mixed solution while heating and stirring, and then standing and reacting to form a B-O-Si covalent bond, thereby obtaining the super-hydrophobic antifouling coating material. After the fabric is subjected to immersion treatment by the super-hydrophobic antifouling coating material, a good dynamic hydrophobic effect is shown, the original air permeability and moisture permeability of the fabric are hardly influenced, and compared with the original fabric, the air permeability is reduced by 1.9-6.6%, and the moisture permeability is reduced by 3.2-4.8%; after the super-hydrophobic antifouling coating fabric is worn and damaged by washing, the super-hydrophobic performance can be recovered under the condition of standing for 180 minutes or heating at 110 DEG C for 30 minutes.

The application provides an antifouling coating material, an antifouling coating and a preparation method and application thereof. The antifouling coating prepared from the antifouling coating material provided by the application has a water contact angle of 105.8-161.5 degrees and a sliding angle of 1.5-24.1 degrees in a wavelength range of 200-2500 nm; a light absorption rate of 65.7-98.3 %; and a maximum light-heat surface temperature of 45.1-82.8 DEG C under 1 solar light intensity. Moreover, the antifouling coating has synergistic antifouling of superhydrophobic low adhesion and biological repellence, wide-spectrum high-efficiency and controllable light-heat antifouling capacity, all-weather antifouling capacity facing the air-water interface of the sea, and excellent mechanical durability and light-heat / wetting performance stability.

The present invention relates to antifouling paint compositions comprising a combination of a binder or base elastomer, a solvent capable of dissolving the binder, and copper salt and / or copper particles. The binder or base elastomer is selected from PIB, BIMS, or PIB mixed with BIMS.

The invention relates to an alloy self-repairing antifouling coating for ships and a preparation method of the alloy self-repairing antifouling coating. The alloy self-repairing antifouling coating is prepared from components of raw materials in parts by weight as follows: 40-60 parts of modified epoxy resin, 10-25 parts of multifunctional packaging alloy microspheres, 5-15 parts of a dynamic cross-linking agent, 3-10 parts of nano reinforcing filler and 1-5 parts of an auxiliary. The surface of the modified epoxy resin is modified by a fluorine-containing surfactant and / or polyurethane. The fluorocarbon chain segment and / or the polyurethane chain segment are / is introduced into the epoxy resin, so that the coating is endowed with excellent anti-scouring performance and a long-term self-maintaining antifouling function.

The present application belongs to the technical field of antifouling coating, and particularly relates to an enzyme-containing organic silicon fouling release type antifouling coating and a preparation method thereof. The coating is mainly composed of amphiphilic functional polymer and antifouling enzyme. The antifouling enzyme is fixed by the amphiphilic functional polymer containing amino groups, and the antifouling enzyme is kept active by the hydrophilic property of the amphiphilic functional polymer. The enzyme-containing organic silicon fouling release type antifouling coating is prepared by adding the amphiphilic functional polymer immobilized antifouling enzyme into an organic silicon elastomer system. The organic silicon chain segment is used as an oleophilic part, and the antifouling enzyme is used in combination with the amphiphilic functional polymer. The stability of the antifouling enzyme in the organic solvent system and the seawater environment is ensured, the organic silicon elastomer coating has good antifouling performance and good environmental friendliness, the antifouling performance is further improved, the enzyme immobilization technology can be applied to the surface antifouling of marine ships and structures, and the enzyme immobilization technology can be applied to the pharmaceutical industry and daily chemical industry.

The environment-friendly packaging corrugated paper comprises two corrugated board bodies, corrugated supporting columns are fixedly connected to the inner walls of the corrugated board bodies, through holes are formed in one sides of the outer surfaces of the corrugated supporting columns, and the inner walls of the corrugated supporting columns are fixedly connected with the inner walls of the corrugated board bodies. Mounting cavities are formed in the inner walls of the corrugated supporting columns and communicate with the through holes. According to the environment-friendly packaging corrugated paper with the antibacterial and antifouling coating, through arrangement of the corrugated paper board body, the corrugated supporting columns, the through holes, the mounting cavities and the transverse plates, when the environment-friendly packaging corrugated paper is used, the corrugated paper board body can be supported through arrangement of the corrugated supporting columns and the transverse plates, and therefore the rigidity of the corrugated paper board body in the using process is improved; the corrugated main board main body is not easy to bend, so that the mechanical strength of the corrugated paper can be improved, the phenomenon of deformation caused when an object is packaged and transported is avoided, and the use strength of the corrugated paper is improved.

The invention discloses a low-surface-energy active and passive synergistic antifouling coating and a preparation method thereof, and belongs to the technical field of marine antifouling materials. The preparation method of the antifouling coating comprises the following steps: S1, mixing acetone and xylene, and stirring in a nitrogen atmosphere to form a mixed solvent; s2, adding vinyl-terminated organic silicon resin and acrylic resin into the mixed solvent, stirring and heating to obtain a coating base solution; s3, adding an initiator into the coating base solution, and continuously stirring and heating for reaction; s4, after the reaction is finished, cooling the coating base solution, and adding a functional filler to form a coating solution; and S5, the coating liquid is coated and then dried, and the low-surface-energy active and passive synergistic antifouling coating is obtained. The low-surface-energy active and passive synergistic antifouling coating prepared by the invention solves the problem that environmental protection property and long-term effect cannot be considered at the same time due to single antifouling mechanism in the existing marine antifouling technology, and has a wide application prospect in the technical field of marine antifouling materials.

The utility model discloses breathable dirt-resistant knitted vamp cloth which aims at solving the problems that vamp cloth of an existing shoe is poor in breathability and not easy to clean, beriberi is easily induced, and body health of people is affected. The vamp cloth comprises an outer-layer fabric, a middle-layer fabric and an inner-layer fabric, the outer-layer fabric is formed by knitting first yarn, the surface of the first yarn is coated with an antifouling coating, the middle-layer fabric is formed by knitting second yarn, and the inner-layer fabric is sewn and fixed with the outer-layer fabric and the middle-layer fabric through sewing threads. According to the utility model, the outer layer fabric, the middle layer fabric and the inner layer fabric are arranged, the outer layer fabric and the middle layer fabric are formed by knitting the yarns, and the surface of the first yarn is coated with the antifouling coating, so that the fabric has the advantages of better air permeability, wear resistance and convenience in cleaning; regeneration and reproduction of various microorganisms such as fungi and molds can be effectively resisted, the odor in the shoes is reduced, and the comfort of the vamp cloth is improved.

The utility model relates to a coating device for antibacterial antifouling artificial leather processing, including base, material dropping mechanism and scraper blade, the top of base is fixedly connected with the main frame, the inside of main frame is fixedly connected with the support table, the side edge of main frame is provided with the sub-frame, the inside of sub-frame is provided with the transmission roller, the top of main frame is provided with the support seat, and the support seat is provided with the material dropping mechanism. The top of the supporting base is fixedly connected with a supporting frame, the top of the supporting frame is provided with an electric cylinder, the bottom output end of the electric cylinder is provided with a piston rod, the bottom of the piston rod is provided with a lifting base, and the scraper is installed at the bottom of the lifting base. The number of the supporting frames, the electric cylinders, the lifting bases and the scraping plates is multiple, the smearing mechanism can be conveniently and rapidly adjusted, time is saved, the working efficiency is improved, the smearing machining requirements of leather materials with different thicknesses are met, the precision is high, and the working quality is guaranteed.

The utility model discloses a curtain with a formaldehyde removal function, the curtain comprises a nylon cloth layer, a fluffy cloth layer, an antifouling coating, a formaldehyde removal auxiliary agent coating and a silver colloid coating, the first surface layer of the nylon cloth layer and the first surface of the fluffy cloth layer are adhered to each other and jointly serve as a bearing main body; the formaldehyde removal assistant coating is uniformly coated on the second surface of the fluffy cloth layer, and the silver colloid coating is uniformly coated on the second surface of the nylon cloth layer; the antifouling coating is arranged on the outer surface of the formaldehyde removal auxiliary agent coating.

The invention discloses an anti-adhesion antifouling coating as well as a preparation method and application thereof. The preparation method of the anti-fouling coating comprises the following steps: 1) carrying out hydroxyl activation treatment and amino functionalization treatment on a substrate to obtain an amino-modified substrate; 2) arranging an initiator modification layer on the surface of the amino-modified substrate obtained in the step 1); and 3) dropwise adding a polymerization solution on the surface of the substrate provided with the initiator modification layer to form a solution layer, and carrying out a polymerization reaction under an illumination condition to obtain the anti-adhesion antifouling coating. The chip with anti-adhesion and anti-fouling characteristics is prepared, the coating with good uniformity and consistency can be prepared only through a small amount of monomers and catalysts, production is convenient and fast, and cost and environment burden are small.

This invention discloses a low surface energy active-passive synergistic antifouling coating and its preparation method, belonging to the field of marine antifouling materials technology. The preparation method of the antifouling coating includes the following steps: S1, mixing acetone and xylene and stirring under a nitrogen atmosphere to form a mixed solvent; S2, adding vinyl-terminated silicone resin and acrylic resin to the mixed solvent, stirring and heating to obtain a coating base liquid; S3, adding an initiator to the coating base liquid and continuously stirring and heating to react; S4, after the reaction is complete and the coating base liquid cools, adding functional fillers to form a coating liquid; S5, coating the coating liquid and drying to obtain a low surface energy active-passive synergistic antifouling coating. The low surface energy active-passive synergistic antifouling coating prepared by this invention solves the problem in existing marine antifouling technologies where the single antifouling mechanism prevents the simultaneous consideration of environmental friendliness and long-term effectiveness, and has broad application prospects in the field of marine antifouling materials technology.

The invention discloses a tannic acid-assisted antifouling coating for an inner seawater system as well as a preparation method and application of the tannic acid-assisted antifouling coating. According to the invention, tannic acid is used as an anchoring part of the antifouling coating to play a good fixing role on the surface of a base material through the adsorption effect, and then a physical interval is formed between tannic acid and the active center of protease through the connection of a hydrophilic substance in the middle layer, so that the conformation change or active site blockage possibly caused by tannic acid to protease is reduced, and the anti-fouling effect of tannic acid is improved. The activity of the protease is better maintained, and meanwhile, enough sites are provided for the protease, so that the protease can be effectively fixed on the surface of a base material to form an antifouling coating. Protein components in a biofilm matrix can be effectively degraded due to existence of protease on the surface of the antifouling coating, so that adhesion of bacteria and algae is prevented, and the antifouling coating has excellent antibacterial and anti-algae performance. The preparation method is simple, convenient, rapid, low in cost and suitable for preparation of the protective coating of the marine equipment and facilities in special scenes.

Provided is a composition for forming a high-gloss coating film which, despite having a comparatively slow coating film dissolution rate, exhibits good long-term antifouling performance, and in which coating film anomalies such as cracks do not occur even after long-term immersion in seawater.　The present invention provides an antifouling coating composition comprising a copolymer A, a rosin ester B, another rosin component C, and an antifouling agent D, wherein: the copolymer A is a copolymer of a monomer (a1) and an ethylenically unsaturated monomer (a2) other than the monomer (a1); the monomer (a1) is represented by general formula (1); the rosin ester B is a reaction product of a polyalcohol (b1) and a rosin or rosin derivative (b2); and the other rosin component C is a rosin or rosin derivative, or a metal salt of a rosin or rosin derivative.

The application relates to a two-component main-chain degradable and side-chain hydrolytic marine antifouling paint and a preparation method thereof, and relates to the technical field of marine antifouling paint. The paint comprises A component and B component. The A component comprises the following components in parts by weight: main-chain degradable and side-chain hydrolytic marine antifouling resin 30-60 parts, silane coupling agent 0-2 parts, red cuprous oxide 0-30 parts, organic antifouling agent 0-20 parts, pigment and filler 2-40 parts, thixotropic agent 0-1 part, anti-sagging agent 0-3 parts, and solvent 0-5 parts. The B component is a curing agent containing isocyanate groups. The prepared antifouling resin has excellent main-chain degradability and side-chain hydrolysis performance. During use, the marine antifouling resin can continuously release acid substances which are abhorred by marine microorganisms. Even in a static state, the coating surface can be gradually renewed through main-chain degradation, so that the antifouling effect is well achieved.

The invention discloses an in-situ self-film-forming antifouling material based on phosphate groups as well as a preparation method and application of the in-situ self-film-forming antifouling material. According to the preparation method, the compounding of a phosphatide component and an antifouling functional component is realized in a polymerization process, and then in order to achieve effective adsorption, the phosphatide component reacts with halosilane and a strong nucleophilic reagent to hydrolyze to generate a phosphate group with a strong coordination effect, so that the antifouling material has a strong anchoring effect. The antifouling material is prepared into a solution system with required concentration and can form a film to form an antifouling coating when being in contact with a metal surface, and the obtained antifouling coating can resist bacteria and fouling and has an anti-corrosion effect.

The application discloses a modified device and method applied to nano-silica antifouling coating agents, the modified device comprises a plasma activation module, an ion beam assisted deposition module, an ultrasonic cavitation module, a vacuum adsorption module and a low-temperature curing unit; the modified method comprises the following steps of S1, plasma pretreatment: under a mixed gas atmosphere, Ar + beam is used for bombarding the surface of nano-silica; S2, in-situ synergistic grafting modification: a silane coupling agent KH-570, a perfluorooctyl triethoxysilane and an ionic liquid modifier are mixed, ultrasonic dispersion is performed for 30 min, and then vacuum adsorption is performed to direct film formation; S3, ion beam assisted deposition of a conductive layer: ITO conductive layers and fluorocarbon shell layers are alternately deposited in a vacuum cavity; S4, low-temperature curing: O ‑ beam triggers fluorocarbon bond rearrangement, UV-LED irradiation and far infrared heating to 75 DEG C, the crosslinking density is greater than or equal to 85%, and the prepared nano-silica antifouling coating agent has excellent antistatic property, transmittance and wear resistance, and higher adhesion.

The invention discloses an easy-to-clean dust cup of a dust collector, and belongs to the technical field of cleaning electric appliances, the easy-to-clean dust cup comprises a dust cup body, the surface of the dust cup body is provided with a nano antifouling coating, and the nano antifouling coating is sprayed on the dust cup body. The nano antifouling coating is composed of nano silicon dioxide doped with nano tungsten trioxide and nano tin oxide. Compared with the prior art, the nano antifouling coating is additionally arranged inside and outside the dust cup, can form a fine protective film on the surface of the dust cup, has a self-repairing function, and can inhibit static electricity on the surface of a base material, so that stains are not easily attached to the surface of the base material, and the attached stains can be self-cleaned even if encountering water; and the cleanness of the dust cup is always kept.

The invention discloses a self-film-forming degradable marine antifouling coating as well as a preparation method and application thereof. The antifouling paint is prepared from the following components in parts by weight: 1 part by weight of RAFT (Reversible Addition-Fragmentation Chain Transfer) agent, 40 to 200 parts by weight of N-isopropylacrylamide, 0 to 20 parts by weight of degradable functional monomer, 0 to 10 parts by weight of hydrophilic monomer, 0.3 part by weight of catalyst and 100 to 550 parts by weight of organic solvent. The antifouling paint disclosed by the invention has self-film-forming performance, biodegradability and coating stability, and also has excellent fouling resistance. The coating prepared from the antifouling paint can meet the antifouling requirement of the seawater pipeline, the defects that the antifouling coating is difficult to construct in the pipeline and the dosage of an antifouling agent is large are overcome, and a simple and convenient antifouling strategy is provided for antifouling of the seawater pipeline.

The invention relates to the field of antifouling coatings, and particularly discloses a green environment-friendly water-based industrial antifouling coating and a preparation method thereof. The antifouling paint comprises 40-55% of bio-based FEVE resin, 8-15% of a bio-based functional additive, 5-8% of nano titanium dioxide, 8-12% of wollastonite powder, 5-7% of calcium carbonate, 3.0-4.5% of other auxiliaries and the balance of water, wherein the bio-based functional additive comprises palm oil fatty glyceride, chitosan nanoparticles and a bamboo fiber / nano cellulose compound. According to the invention, the vegetable oil modified FEVE resin is used as a core raw material to replace a traditional petroleum-based raw material, and is matched with a relatively small addition amount of the bio-based functional additive and fillers such as nano titanium dioxide, wollastonite powder and calcium carbonate, so that the antifouling paint with environmental friendliness, hydrophobicity, stain resistance and weather resistance is prepared, the purpose of long-acting antifouling is achieved, and the environment-friendly, hydrophobic and weather-resistant effects are achieved. Moreover, the production cost is lower, and the application prospect is very wide.

This invention relates to the field of coating technology, and particularly to a functionalized antifouling nanoparticle and its preparation method, as well as an energy-saving, drag-reducing, and environmentally friendly antifouling coating and its preparation method. The preparation method of the antifouling nanoparticle includes the following steps: polyethylene glycol methyl ether acrylate and a first silane coupling agent are heated and reacted for a certain time to obtain a functionalized silane coupling agent; a lactone and N,N-dialkyl-3-aminopropyltrimethoxysilane are stirred and mixed in solvent B to react and obtain silane-coupled betaine; the functionalized silane coupling agent, silane-coupled betaine, and a second silane coupling agent are added to a dispersion formed by a catalyst and zinc oxide nanoparticles and heated to react, thereby obtaining the antifouling nanoparticles. The antifouling nanoparticles obtained by this invention can be used in coating systems to prepare antifouling coatings. This antifouling coating formulation does not contain antifouling agents, is environmentally friendly, and the resulting coating has good antifouling effect. Furthermore, after being washed by seawater for a period of time, the surface of the coating becomes smoother, effectively reducing water flow resistance.

This invention belongs to the field of coating preparation technology and provides an aerogel-reinforced antifouling coating for ships and its preparation method. A fluorosilicone prepolymer is prepared by reacting perfluorohexyl ethyl acrylate with a silane coupling agent under the action of azobisisobutyronitrile (AIB). This prepolymer is then mixed with hydroxyl-terminated polydimethylsiloxane and PEEK nanofibers to obtain a resin matrix. An aerogel is prepared by hydrolyzing tetraethyl orthosilicate to form a SiO2 gel, followed by solvent replacement and perfluorinated surface modification. A chromium-based metal-organic framework composite material is prepared by hydrothermal method and then composited with an ionic liquid to obtain an ionic liquid composite additive. Microsphere additives are prepared by emulsion polymerization, and surface structure properties are further controlled by etching processes. The resin matrix, aerogel, ionic liquid composite additive, microsphere additive, and solvent are mixed to obtain the aerogel-reinforced antifouling coating for ships.

This invention discloses an organosilicon marine antifouling coating suitable for static marine facilities. The coating process involves reacting capsaicin with unsaturated acid anhydride monomers to eliminate the active free radical scavenging phenol groups and synthesize capsaicin unsaturated esters. These esters serve as inhibitors for subsequent free radical copolymerization. The capsaicin unsaturated esters then undergo free radical polymerization with unsaturated silane curing agent monomers to obtain capsaicin-modified silane curing agents. These modified organosilicon marine antifouling coatings are then prepared based on this modified silosilicon coating. In actual service, especially in static seawater environments, the low surface free energy of this coating inhibits the adhesion of fouling organisms. Simultaneously, the capsaicin groups stimulate fouling organisms, driving them away from the coating surface and significantly improving the antifouling effect of the coating on static marine facilities. This coating is particularly suitable for various static marine facilities subjected to long-term static immersion in seawater, achieving fouling prevention without relying on seawater erosion.

Provided is an antifouling coating composition comprising a silicon atom-containing resin. The silicon atom-containing resin includes a constituent unit (A) derived from a monomer (a) having at least one kind of silicon atom-containing group selected from the group consisting of a group represented by a formula (I), a group represented by a formula (II), a group represented by a formula (III), and a group represented by a formula (IV); and a constituent unit (B) derived from a monomer (b) which is a polyfunctional (meth)acrylic acid ester having two or more (meth)acryloyl groups.